The invention relates to improvements in firearms employing consumable, caseless ammunition.
In the military, there is an interest in a form of ammunition for rifles and machine guns which does not require a metal case to house propellant. While there are a number of reasons for this interest, one compelling reason centers on the fact that the metal case comprises nearly 50% of the weight of each cartridge. Thus, for ammunition of like weight, a successful "caseless" format would afford a 2:1 firepower advantage over conventional weapons.
Previous proposals in the caseless field are exemplified in U.S. Pat. No. 3,474,560 issued to Ramsay on Oct. 28, 1969; No. 3,483,793 issued to Ramsay on Dec. 16, 1969; No. 3,641,692 issued to Wells on Feb. 15, 1972; Nos. 3,641,867, 3,828,676, and 3,990,347 issued Feb. 15, 1972, Aug. 13, 1974, and Nov. 9, 1976, respectively, to the present inventor, and No. 3,772,123 issued to Parisi on Mar. 27, 1973. The disclosures in U.S. Pat. Nos. 3,641,867, and 3,828,676, and 3,990,347 of this inventor are incorporated by reference herein as if set forth at length.
Some prior proposals center around the employment, in conventional firearms, of a cartridge which is physically similar to the metal cartridge in that both the projectile and caseless propellant are packaged or fixed together. During loading, the cartridge would be engaged by a bolt and rammed forwardly into the firing position. In such an instance, the cartridge propellant must be exceedingly strong to withstand the forces encountered since the bolt, especially in the typical reciprocating-action automatic firearm, drives the cartridge against fixed chamber shoulders with considerable closing velocity. It has not proven feasible, however, to achieve the required degree of cartridge strength without interlacing the propellant with foreign materials which, upon firing, leave unacceptable high amounts of residue.
Some proposals in the caseless field fail to provide for convenient extraction of an unspent projectile. That is, in the event of a misfire, substantial efforts and disassembly of the firearm may be necessary to remove the projectile and/or cartridge.
Other problems in the caseless area involve complicated mechanisms for unlocking the bolt for recoil and recocking motion. It would be desirable to provide a simplified unlocking system.
Although it has been heretofore proposed to harness the recoil motion of the firing pin to unlock the bolt, such proposals involve complex systems which do not enable the firing sequence to be initiated with the bolt in a forward, locked position. It would be desirable to avoid this problem as well as to provide a system where a spring activates the firing pin without being subjected to excessive stressing by firing pin recoil.
It has been previously proposed to obturate around a firing pin in a manner requiring the formation of grooves in the pin to receive sealing rings. This, however, weakens the firing pin.
Previous firearm designs render impracticable the use of replacement bolts. It would be desirable if bolts which have become fouled could be replaced conveniently in the field.
Proposals have been made for providing anti-recoil muzzles at the discharge end of a barrel. The muzzle is to be provided with a reaction surface to be acted upon by ignition gases. However, the reaction surface may have a tendency to accumulate carbon deposits. Moreover, the surface of the barrel opposite the reaction surface is acted upon by the ignition gases to create recoil forces which, in effect, cancel-out the effectiveness of the anti-recoil muzzle.
It is, therefore, an object of the present invention to eliminate problems such as these without unduly complicating firearm operation.
It is a further object of the present invention to enable caseless ammunition to be effectively and efficiently employed in firearms.
It is another object of the invention to minimize the shock to which caseless propellant is subjected in a firearm, while providing for the extraction of unspent propellant and projectile.
It is another object of the invention to provide a bolt locking mechanism of such simplicity that it is practical to manufacture interchangeable or reserve bolts.
Another objective is to provide a bolt which is removable for cleaning and maintenance purposes.
It is a further object of the invention to provide a novel bolt locking mechanism in which the bolt locks itself and is unlocked by the recoil action of a firing pin.
It is another object of the invention to provide a novel firearm in which the firing pin is urged by spring power to a firing position, and the firing pin is subjected to recoil action to unlock the bolt without imposing undue stress upon the spring.
It is an additional object of the invention to provide novel means for obturating around a firing pin without requiring the placement of grooves in the firing pin.
It is another object of the invention to provide an effective anti-recoil muzzle and means for resisting carbon build-ups on the reaction surface.
It is still a further object of the invention to provide a novel propellant cartridge which is inexpensive to manufacture, leaves virtually no residue, and is easily handled within the firearm.